A capacitance video recording and playback system has been disclosed in U.S. Pat. Nos. 3,842,194, 3,842,217 and 3,909,517 to Clemens, incorporated herein by reference. According to this system, disc replicas can be prepared having geometric variations in a spiral groove in the disc surface which correspond to capacitance variations representative of video signals. The discs are coated first with a thin conductive metal layer and then with a dielectric layer. A metal stylus completes the capacitor and, during playback, rides upon the dielectric coating and detects dimensional variations in the groove. These variations are reconstituted in electrical signal form and converted back to video information suitable for display by a television receiver. A suitable system for converting the information representing capacitance variations to electrical signals is described in copending application of Kawamoto et al, "Pickup Circuitry for a Video Disc Player", Ser. No. 743,144 filed Nov. 18, 1976 now U.S. Pat. No. 4,080,625.
Since the relief pattern and the groove are of very small dimensions, e.g., there are 5,000-10,000 grooves per inch (1968-3937 grooves per centimeter), much research and expense have been required to learn how to put down metal and dielectric layers which conform to the relief pattern, are thin enough so they do not fill the grooves and yet are thick enough so as to form a coherent, abrasion resistant and pinhole free layer.
It will be apparent that if the metal and dielectric layers could be eliminated, with no substantial loss of signal or increase in noise level on playback of the disc, it would be a great advance as far as cost savings in manufacturing are concerned.